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RISS 인기검색어
- 검색키워드
- 저자 : Etsuo Sakai (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
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Influence of the Character of Fly Ash on the Fluidity of Fly Ash Cement Paste
이승헌,Etsuo Sakai 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.5
The Influence of the character of fly ash on the fluidity of cement paste with a polycarboxylic acid type superplasticizer was investigated in connection with the particle size distribution, unburned carbon content, specific surface area and shape of the fly ash. The fluidity of the fly ash cement paste with an added 20 vol% fly ash increases with an increasing roundness of the fly ash and it decreases with an increasing n-value of the fly ash cement. There is a linear correlation between the roundness/n-value and the fluidity of fly ash cement paste.
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Rheological behavior of a slag cement paste prepared by adjusting the particle size distribution
Hae-Jeong Hwang,Etsuo Sakai,Seung-Heun Lee 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4
In this study, the particle size distributions of a cement powder system were adjusted using granulated blast furnace slag powder, Blaine 2250 cm²/g and 8300 cm²/g, with which it was easy to adjust the particle size distribution to examine how the particle size distribution of the binder effect the rheological properties of the cement paste. In addition, the relationship between the n-value of the Rosin-Rammler function and plastic viscosity is discussed. All of the measured flow curves represent thixotropic behavior. Also the hysteresis area was smaller with more added coarse particles such as OBB-4 and OBB-2. When the combination was based on a combination of 20-25 vol% fine particles, 30-40 vol% OPC and 40-45 vol% coarse particles in the total volume, a high fluidity and low yield strength was achieved. The plastic viscosity rises, as the n-value decreases and most of the samples indicated that the n-value was correlated with the plastic viscosity. However, in case of a sample which over 30 vol% of fine particles, the plastic viscosity decreased although the n-value decreased. In this study, the particle size distributions of a cement powder system were adjusted using granulated blast furnace slag powder, Blaine 2250 cm²/g and 8300 cm²/g, with which it was easy to adjust the particle size distribution to examine how the particle size distribution of the binder effect the rheological properties of the cement paste. In addition, the relationship between the n-value of the Rosin-Rammler function and plastic viscosity is discussed. All of the measured flow curves represent thixotropic behavior. Also the hysteresis area was smaller with more added coarse particles such as OBB-4 and OBB-2. When the combination was based on a combination of 20-25 vol% fine particles, 30-40 vol% OPC and 40-45 vol% coarse particles in the total volume, a high fluidity and low yield strength was achieved. The plastic viscosity rises, as the n-value decreases and most of the samples indicated that the n-value was correlated with the plastic viscosity. However, in case of a sample which over 30 vol% of fine particles, the plastic viscosity decreased although the n-value decreased.
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Influence of the Character of Fly Ash on the Fluidity of Fly Ash Cement Paste
Lee, Seung-Heun,Sakai, Etsuo The Korean Ceramic Society 2010 한국세라믹학회지 Vol.47 No.5
The Influence of the character of fly ash on the fluidity of cement paste with a polycarboxylic acid type superplasticizer was investigated in connection with the particle size distribution, unburned carbon content, specific surface area and shape of the fly ash. The fluidity of the fly ash cement paste with an added 20 vol% fly ash increases with an increasing roundness of the fly ash and it decreases with an increasing n-value of the fly ash cement. There is a linear correlation between the roundness/n-value and the fluidity of fly ash cement paste.
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The Fluidity of Cement Pastes with Fly Ashes Containing a Lot of Unburned Carbon
Lee, Seung-Heun,Kawakami, Akira,Sakai, Etsuo,Daimon, Masaki The Korean Ceramic Society 2003 한국세라믹학회지 Vol.40 No.3
Fly ashes containing 6.1~16.5 wt% of unburned carbon were treated thermally at 500$^{\circ}C$ for 3 h and thus, the content of unburned carbon was decreased below 2.1 wt%, the range of particle size distribution became narrower and the mean particle size became smaller. Besides, the properties of particles in fly ashes were improved, particularly the particle shape became close to a spherical type. The fluidity of cement pastes containing fly ashes treated previously at 500$^{\circ}C$ for 3 h was increased much than that of cement pastes containing original fly ashes. When the added amount of superplasticizer was over the saturation amount, there was no correlation between the amount of unburned carbon in fly ashes and the apparent viscosity of cement pastes actually. On the contrary, when the added amount of superplasticizer was below the saturation amount, there was a correlation.
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디지털 이미지 분석을 이용한 Fly Ash의 원형지수 측정
Lee, Seung-Heun,Kim, Hong-Joo,Bae, Soon-Muk,Lee, Won-Jun,Sakai, Etsuo,Daimon, Masaki 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.8
미분탄 화력발전소에서 보일러의 부하를 변화시켰을 때 전기집진기에서 단별 채취한 fly ash에 대해서 디지털 이미지 분석을 이용하여 원형지수를 검토하였다. 원형지수 측정은 다음과 같은 다섯 단계, 즉 ① 이미지 획득, ② 이미지 전처리, ③ 검출, ④ 이미지 후처리, ⑤ 측정의 단계를 거쳐 이루어 졌다. Fly ash의 평균 원형지수는 0.78∼0.83의 범위를 나타냈으며, 같은 위치에 있는 호파에서 채취한 fly ash는 보일러의 부하에 관계없이 유사한 원형지수 값을 나타냈다. 그리고 첫 번째 호파에서 세 번째 호파로 갈수록, 즉 fly ash의 평균 입경이 작아질수록 원형지수는 증가하는 경향을 나타냈다. This paper investigates circularity of fly ashes using the digital image processing. Fly ashes directly collect from electrostatic precipitator when the load of conditions of boiler are changed at a coal-fired power plant. Circularity measurement can be accomplished in five steps: ① image acquisition, ② grey image processing, ③ detection the component to measure ④ binary image processing ⑤ feature measurement. The mean circularity of fly ashes is in the range of 0.78 to 0.83. fly ashes collected from the same hopper has similar circularity regardless of the load of boiler and circularity increases as going from the 1st hopper to 3rd one, namely as particle size become finer.
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Zainal Arifin Ahmad,Bun Kim Ngun,Hasmaliza Mohamad,Etsuo Sakai 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3
The effects of rice husk ash (RHA) and fume silica (SF) in both binary and ternary systems on the properties of cement pastes and the compressive strength of concretes were studied. The amount of cement replacement in both systems was 15%. The free calcium hydroxide (Ca(OH)2) content was analyzed using XRD and TG/DTA for the hardened cement pastes. The results showed that the amount of Ca(OH)2 decreased significantly the curing ages for all blended cement pastes. At 28 days, the amount of Ca(OH)2 in OPC is 17.31%, 8.18% in RHA and 6.43% in SF replacements, respectively. The ternary system similarly indicates a significant reduction of Ca(OH)2 content. The compressive strength of concretes was improved significantly by blending the aforementioned materials in both systems. In the ternary system, the concretes containing 7.5%SF and 7.5% RHA gave remarkable improvement in the compressive strength. For example after 90 days curing, the strength is 57.8 MPa whilst only 47.5 MPa for OPC. Therefore, the application of proper ratios of RHA and SF in a ternary system is able to increase the properties of the concrete.
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